Botanical classification: Euphorbia amygdaloides var. robbiaexc3x97Euphoriba characias. 
Variety denomination: xe2x80x98Blue Lagoonxe2x80x99.
The present invention relates to a new and distinct cultivar of a hardy, suffrutescent perennial of the genus Euphorbia, known by the cultivar name of xe2x80x98Blue Lagoonxe2x80x99. The genus Euphorbia is a member of the family Euphorbiaceae.
The new cultivar originated as a garden cross between Euphorbia amygdaloides var. robbiae (seed parent, unpatented) and Euphorbia characias (pollen parent, unpatented). The cross was discovered when growing out the seedlings of Euphorbia amygdaloides var. robbiae. Euphorbia characias was the only other Euphorbia species in bloom and the seedling has the characteristics of both parents.
This new cultivar is characterized by:
1) Persistent winter foliage like the seed parent Euphorbia amygdaloides var. robbiae. 
2) Blue green foliage.
3) Large plant size like the pollen parent Euphorbia characias. 
4) Tall, chartreuse colored inflorescences.
5) Bract colors past maturity are orange and russet extending the showiness of the bloom time.
6) Habit is a basal clump which spreads by underground rhizomes like the seed parent.
7) Sterile, so no seed or unwanted seedlings are produced.
8) Not susceptible to winter wet which causes rot in many Euphorbia species.
9) Excellent vigor, rapid growth.
Asexual propagation by tissue culture using standard micropropagation techniques with terminal shoots as done in Canby, Oreg., shows that the foregoing characteristics and distinctions come true to form and are established and transmitted through succeeding propagations. This new cultivar has been reproduced only by asexual propagation (division and tissue culture). Each of the progeny exhibits identical characteristics to the original plant. The present invention has not been evaluated under all possible environmental conditions. The phenotype may vary with variations in environment without a change in the genotype of the plant.